1. Field of the Invention
This invention relates to an image pickup apparatus which automatically pursues an object and further relates to a driving device which is suitable for driving the image pickup apparatus.
2. Description of the Prior Art
A conventional image pickup apparatus using a ginbal mechanism is shown in FIG. 24. An image pickup optical lens system and an image pickup device such as CCD (Charge Coupled Device), which are not shown in the figure, are contained in a cylindrical image pickup unit 100. The image pickup device is connected to a control unit 130 via a cable K1. The image pickup unit 100 is rotatably pivoted by a shaft 101 on a rotary frame 102. Thus, the image pickup unit 100 can be rotated around Y-axis. The rotary frame 102 is rotatably pivoted by a shaft 103 on a fixed frame 104. Thus, the image pickup unit 100 can be rotated around X-axis. The X-axis is substantially horizontal and stationary. The Y-axis moves on a plane perpendicular to the X-axis.
A gear 112 fixed on the shaft 101 engages with a gear 111 fixed on a drive shaft of a motor 113. The gears 111 and 112, the motor 113, an encoder (not shown in the figure) configure a Y-axis driving mechanism 110 for controlling an angle and direction of rotation of the shaft 101. The motor 113 and the encoder are connected to the control unit 130 via a cable K2.
Similarly, a gear 122 fixed on the shaft 103 engages with a gear 121 fixed on a rotation shaft of a motor 123. The gears 121 and 122, the motor 123, an encoder (not shown in the figure) configure an X-axis driving mechanism 120 for controlling an angle and direction of rotation of the shaft 103. The motor 123 and the encoder are connected to the control unit 130 via a cable K3.
When the image pickup apparatus automatically pursues an object, the control unit 130 processes an image data picked by the image pickup unit 100 and extracts an image of the object. The control unit 130 calculates a quantity of the displacement for displacing the image of the object to the center of a screen of a display device. The control unit 130 drives the motors 113 and 123 by using the calculated quantity of the displacement. Thus, an optical axis of the image pickup optical lens system of the image pickup unit 100 directs the object.
In the above-mentioned conventional image pickup apparatus, the Y-axis driving mechanism 110 is necessary to be integrated with the image pickup unit 100. Alternatively, the Y-axis driving mechanism 110 is necessary to be disposed inside the image pickup unit 100. Thus, the X-axis driving mechanism 120 must drive not only the image pickup unit 100 and the rotary frame 102 but also the Y-axis driving mechanism 110. The load of the X-axis driving mechanism 120 becomes heavier than that of the Y-axis driving mechanism 110.
Furthermore, the conventional image pickup apparatus needs spaces for providing the cables K1, K2 for connecting the image pickup unit 100, the moving portion of the Y-axis driving mechanism 110 and the control unit 130. Thus, it is difficult to downsize and to lighten the image pickup apparatus.
When dust-proof, humidity-proof, waterproof of the apparatus is considered, not only the image pickup unit 100 but also the Y-axis driving mechanism 110 and the X-axis driving mechanism 120 are sealed into a special housing. As a result, size of the apparatus becomes larger and structure of the apparatus is complicated.